With population growth, industrialization and urbanization, energy consumption has increased fast in recent years, and energy shortage becomes an imminent problem. Nuclear power plants used in many advanced countries have brought about the problems of thermal pollution and nuclear waste. Owing to exhausted energy resources and environmental protectionism, many nations have paid attention to research and utilization of green energy, and numerous researchers have been devoted to developing new energy sources to replace fossil fuels.
The conventional thermal power plants use thermal energy generated by fossil fuels, such as coal, petroleum and natural gas, to convert water into steam, and the steam drives a gas turbine to operate. Then, the gas turbine further drives a power generator to generate electric power. A US patent publication No. 20140013746 may exemplify the conventional technology. The conventional nuclear power plants use uranium-235 as nuclear fuel, which undergoes nuclear fission inside a nuclear reactor and releases a great amount of thermal energy. Next, high-pressure circulating cooling water absorbs the thermal energy and becomes steam in a steam generator. Next, the high-temperature and high-pressure steam drives a gas turbine to operate. Then, the gas turbine further drives a power generator to generate electric power. A US patent publication No. 20130121449 may exemplify the conventional technology.
However, the fossil fuel-based thermal power plants would generate waste heat, carbon dioxide, sulfur dioxide, suspended particulates, etc. and cause air pollution. Besides, the reserve of fossil fuels is not unlimited but will be exhausted one day. The reactors of nuclear power plants carry a great amount of radioactive materials, which will become nuclear waste after the depletion of the nuclear fuel. Besides, nuclear power plants cause more serious thermal pollution. Therefore, developing power generation technologies meeting the demands of green energy and environmental protection is an urgent mission for governments and researchers.